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Genetic counseling: Hemifacial Microsomia
Hemifacial Microsomia (a.k.a. Goldenhar Syndrome, Oculoauriculovertebral Dysplasia, OAV Syndrome, Facio-Auriculo-Vertebral Spectrum, First & Second Branchial Arch Syndrome) Introduction *Hemifacial Microsomia is a condition that affects the growth of the face. It is predominantly unilateral and involves the ear, mouth, and mandible. This disorder is extremely variable with many transitional forms affecting different systems (for example, Goldenhar Syndrome is used when there is ocular and vertebral involvement), which suggests that this disorder is a range along a continuous spectrum. Genetic Etiology *HFM has an unknown etiology, but is usually sporadic. However, a few cases have had a positive family history suggesting autosomal dominant, autosomal recessive, or multifactorial. The estimated recurrence in first-degree relatives is about 2%, but the minor features of the disorder may be more commonly noted in relatives. The chances of having another child with Hemifacial Microsomia are less than 1%. An affected person has an approximately 3% chance of passing it on to their children. *HFM is thought to be caused by abnormal changes in blood vessels and the disruption of the blood supply during embryonic development (early vascular disruption) at about 30-45 days of gestation. This results in the destruction of differentiating tissue in the first and second branchial arches, from which certain ligaments and bones of the face, parts of the skull, and the middle ear develop. *No DNA abnormality has been identified. However, it has also been noted that certain teratogens (Thalidomide, Primidone, and Accutane) have produced birth defect patterns that are similar to the HFM spectrum. Also, a research study is being done to determine if there is a higher rate of Goldenhar Syndrome found in the children of Gulf War veterans. Incidence *The frequency of occurrence is estimated to be 1 in 3000 to 1 in 5000, and there is a slight male predominance (3:2). Clinical Features *Key features: **Facial - asymmetry (90%). . .right side predominance (62%) **hypoplasia of malar, maxillary, and/or mandibular region **macrostomia (lateral cleft-like extension of the corner of the mouth) **hypoplasia of the facial musculature **frontal bossing **Ear - microtia (malformation of the external ear from complete aplasia to a crumpled, distorted **pinna which is displaces anteriorly and inferiorly) (65%) **accessory preauricular tags and/or pits **middle ear anomaly with variable deafness **Eye - palpebral fissure is somewhat lowered on the affected side **Oral - diminished to absent parotid secretion **anomalies in function or structure of the tongue **malfunction of the soft palate *Associated findings: **prenatal growth deficiency, feeding difficulties **Vertebral - hemivertebrae or hypoplasia of vertebrae, usually cervical (40-60%) **Eye - epibulbar dermoid and/or lipodermoid **strabismus **unilateral coloboma of the superior lid **microphthalmia **Oral - cleft lip, cleft palate (7%) **Cardiac - various forms of heart disease (45-55%) **ventricular septal defect **patent ductus arteriosus **tetralogy of Fallot **coarctation of the descending aorta **Lung - pulmonary agenesis or hypoplasia of the lung **Renal - ectopic and/or fused kidneys **renal agenesis **double ureter **Nervous - mental retardation (10%) **occipital encephalocele **hydrocephalus **agensis of corpus callosum Natural History *Hemifacial Microsomia is congenital and most of the physical characteristics are apparent at birth. However, the facial asymmetry may not become apparent until the child grows (usually by four years of age). Testing *Prenatal diagnosis by ultrasound may be possible if there is severe hypoplasia of the mandible or severe abnormality of the auricle. Management *Most of these patients have normal intelligence. Deafness should be tested for at an early age, and speech therapy is often necessary. Help may be required for feeding problems and encouraging weight gain in early infancy. Any congenital heart defects may require surgery. Plastic surgery may be used to reconstruct the ear, and bone distraction techniques are available to artificially lengthen the jaw bone to improve growth on the face. Children may also need ongoing orthodontic treatment. Differential Diagnoses *Treacher-Collins Syndrome *CHARGE Association *VACTERL Association *Townes-Brocks Syndrome *Branchio-Oto-Renal (BOR) Syndrome *Chromosomal disorders (including Trisomy 9 Mosaicism, Trisomy 18, Ring 21 Chromosome, and Trisomy 22) *Teratogen exposure Psychosocial Issues *Assess development. *Feeding problems? *Cleft lip or other surgical repair? *How are they dealing with the diagnosis? *Have they shared with the family? What were their reactions? *Have they taken the baby out of the house? *How do they feel about the public's response to the facial abnormalities? *Would they like to talk with other families going through the same thing? *How can we be helpful to them? Resources *Hemifacial Microsomia/Goldenhar Syndrome Family Support Network :c/o Kayci Rush :3619 Chicago Avenue :Minneapolis, MN 55407-2603 :(612) 823-3529 *Association of Birth Defect Children (ABDC) :1-800-313-2232 :http://www.birthdefects.org Notes The information in this outline was last updated in 2001. This material has been imported fom the wikibook "Genetic counseling"[ http://en.wikibooks.org/wiki/Genetic_counseling] under the GNU Free Documentation License.